Speech recognition systems are finding increasing use, particularly in voice-controlled user interfaces. Voice-controlled user interfaces are familiar to anyone who performs banking and credit card transactions by telephone. In the past, telephonic banking and credit card service transactions were performed either through interaction with a human agent or by using a keypad of a telephone; now, with increasing frequency telephonic banking and credit card service transactions may be performed using voice commands.
Voice-activated user interfaces are also finding increasing use in portable electronic devices like cellular telephones and personal digital assistants (“PDAs”) with telephonic capabilities. For example, in cellular telephones with voice-activated user interface capability, a user can enter a voice command “Call Bob Smith” in order to initiate a telephone call to a target person (“Bob Smith”). This eliminates the need for the user to enter a telephone number, or to access a contact list containing the telephone number, thereby saving keystrokes. The elimination of keystrokes often enables hands-free modes of operation, which is particularly advantageous when the telephone call is initiated by someone operating an automobile. There is increasing pressure to restrict the operation of cellular telephones by drivers of automobiles, particularly cellular telephones that require hand operation.
Thus, the ability to initiate an operation (e.g., a telephone call) by issuing a voice command to a voice-controlled user interface is particularly advantageous because it saves time and effort previously expended by entering commands using keys or other hand-operated input devices. This advantage ends, though, as soon as a user enters a command not recognized by a speech recognition system associated with a voice-controlled user interface. In such circumstances, a user is often thrust back to old, more tedious modes of operation where a command has to be entered using a combination of keystrokes.
In such situations, where a cellular telephone user is seeking to initiate a telephone call, the user would either have to enter the telephone number directly, or add it to a contact list. Since users of productivity-enhancement devices like cellular telephones and PDAs value the ability of these devices to “grow” with the user by, for example, being able to record and save an extensive and ever-expanding contact list, the fact that this ability may only be partially implemented (if at all) through voice commands is viewed as a particular limitation of voice-activated user interface systems incorporated in such devices. If a user has an extensive contact list, the user might not even initiate a telephone call using the voice command feature, because the user might forget whether the person to be called is even in the contact list and thus capable of being recognized by a voice-activated user interface operating in combination with the contact list.
A further problem is apparent in this description of the prior art. In conventional speech recognition systems, the vocabularies and grammars are fixed. Accordingly, when the user is thrust back upon a keystroke-mode of operation in order to enter new commands, the user will have to enter the new commands with keystrokes every time the new commands are to be performed, since the vocabularies and grammars are fixed. There is no benefit to the speech recognition system associated with the user giving meaning to a command unrecognized by the speech recognition system using keystrokes, since the information entered using keystrokes does not modify the capabilities of the speech recognition system.
Accordingly, those skilled in the art desire speech recognition systems with the ability to “grow.” In particular, those skilled in the art desire speech recognition systems with the ability to identify new words previously unknown to the speech recognition system and to add them to one or more vocabularies and grammars associated with the speech recognition system. In addition, those skilled in the art desire voice activated user interfaces with the ability to learn new commands. Further, when it is necessary to enter commands using keystrokes, those skilled in the art seek speech recognition systems that can be re-programmed though interaction with keys, keyboards, and other command entry controls of an electronic device, so that the speech recognition system benefits from the efforts expended in such activities.